The combination of altitudinal variation and isolation of the Simien Mountains has given rise to a number of rare and endemic species and a high level of diversity. This high endemicity and diversity justifies the inclusion of SMNP in Conservation International’s Eastern Afromontane Biodiversity Hotspot. The remoteness and isolation of the area that determine this endemism has also rendered these isolated populations of species such as the Ethiopian wolf, walia ibex or gelada to be more vulnerable to local extirpation or extinction from many threats.
The altitudinal variation in SMNP means that a wide diversity of plant species are found in the park and endemism has also arisen from its isolation. There are over 1,200 species of plant in SMNP, of which three are found only in the Simien Mountains: Festuca gilbertiana, Rosularia simensis and Dianthus longiglumi. There are three main vegetation zones in SMNP: Montane forest (1,900 to 3,000m), Ericaceous belt (Sub-Afroalpine) (2,700 to 3,700m) and finally the Afroalpine zone (3,700 to 4,533m).
Montane Forest: 1,900 to 3,000m
Montane forests are found on the lower reaches of the escarpment leading towards the lowlands in the northern and western parts of the park. Elders in the area report that other areas around SMNP were once also covered in montane forests. Much of the primary forests have, however been destroyed due to grazing, clearing and settlements, therefore conservation of the remaining areas is of high importance. Biodiversity in the montane forests is much higher than on the high ridges or plateaus.
The most common trees include Juniper (Juniperous procera), Hagenia abyssinica, Olea africana, Cordia Africana, Ficus spp. and Szygium guineense – almost all of these trees are threatened. Other vegetation includes shrubs such as Solanum sessilistellatum. Rosa abyssinica (Abyssinian rose – found only in Africa except for the highlands of Yemen), Primula verticillata, Urtica and species of herbs such as Alchemilla and Thymus.
Mammals that can be seen in the montane zone include vervet monkey, bushpig, grey duiker, black-and-white colobus monkey, leopard, spotted hyena, serval, and hamadryas baboon. Birds include the Abyssinian woodpecker**, Abyssinian catbird*, and Abyssinian oriole**.
Ericaceous belt/ Sub-Afroalpine: 2,700 to 3,700m
The Sub-Afroalpine belt is found mostly on the steep escarpment areas, although scattered Erica forests are also found on the high plateaus. Erica is found in both tree and shrub form and there are also the remains of ancient forests of Giant Heath (Erica arborea) – a shrub common throughout that world that grows to staggering proportions of up to 5m in the Afromontane areas of Ethiopia. Local people often use Erica for fuelwood and building. However, due to its slow regeneration and growth rate, it is at great risk from unsustainable harvesting and overgrazing that prevent regeneration. Efforts to conserve and rehabilitate the Erica areas are thus of high priority.
Other vegetation characteristic of this zone includes a mix of St. John’s Wort (Hypericum revolutum), giant lobelia (Lobelia rhynchopetalum) and Festuca spp. at the higher altitudes over 3,000 m.
Mammals that can be seen include walia ibex*, gelada*, golden (common) jackal, klipspringer, and grey duiker. Birds species include the Abyssinian catbird*, wattled ibis**, thick-billed raven**, and bearded vulture.
Afroalpine: 3,700 to 4,533m
Other vegetation includes grasses such as Festuca spp., collectively known as ‘guassa.’ Like the Erica, these grasses are used by the local people for rope and thatch. The grasses are home to an extremely high density and diversity of Afroalpine rodents (mice, rats, and molerats) that dominate the cold and seemingly barren plateau. They are the natural grazers of the Afroalpine, performing important duties of constantly turning the soil over to mix materials from various levels. Highland swamps (bogs) and lakes also support resident and migratory water birds.
Mammals found in this area include Ethiopian wolf*, walia ibex*, gelada*, serval, spotted hyena, golden (common) jackal and klipspringer. Notable birds include the black-headed siskin*, Ankober serin*, spot-breasted plover*, Abyssinian woodpecker**, Abyssinian long-claw*, white-collared pigeon**, thick-billed raven** and bearded vulture.
* Endemic to Ethiopia
** Endemic to Ethiopia and Eritrea